A type curve approach to estimatingp for ap-normal transformation

The p-normal transformation plays an important role in reservoir characterization for data sets that are neither normally nor log-normally distributed. The key step in the transformation is to estimate the value of pfor a given data set. Even though there are several ways to determine p,these are more inconvenient than the quicker and easier type curve approach to estimate pwe present in this paper. In addition, the method provides the p-normal transformation with a visual interpretation. We demonstrate the technique by analyzing reservoir permeability and porosity data from the East Velma West Block Sims Sand Unit, Oklahoma.     

松科二井深地震反射数据Q值分析及其对含气层位的确定

地震波在地下介质中传播时,地震波能量会出现一定程度的衰减,品质因子Q作为衡量地下岩石吸收衰减属性的重要参数,对描述岩性特征以及预测油气分布具有重要意义。本文针对深地震反射数据,利用基于S变换谱比法的Q值分析技术,获得了更加准确的Q值。以松辽盆地沙河子组为主要目标层,对穿过松科二井的叠后深地震反射剖面进行Q值计算,生成Q值剖面,总结出沙河子组Q值分布特征,同时结合松科二井测井、分层和气测异常资料进行分析,推断沙河子组为含气储层,为下一步深部储层预测提供思路,为东北地区深地勘查工程提供服务。     

Vp/Vs ratio along the Vøring Margin, NE Atlantic, derived from OBS data: implications on lithology and stress field

A total of 13 regional Ocean Bottom Seismograph (OBS) profiles with an accumulated length of 2207 km acquired on the Vøring Margin, NE Atlantic have been travel time modelled with regards to S-waves. The V_p/V_s ratios are found to decrease with depth through the Tertiary layers, which is attributed to increased compaction and consolidation of the rocks. The V_p/V_s ratio in the intra-Campanian to mid-Campanian layer (1.75–1.8) in the central Vøring Basin is significantly lower than for the layers above and beneath, suggesting higher sand/shale ratio. This layer was confirmed by drilling to represent a layer of sandstone. This mid-Cretaceous ‘anomaly’ is also present in the northern Vøring Basin, as well as on the southern Lofoten Margin further north. The V_p/V_s ratio in the extrusive rocks on the Vøring Plateau is estimated to be 1.85, conformable with mafic (basaltic) rocks. Landward of the continent/ocean transition (COT), the V_p/V_s ratio in the layer beneath the volcanics is estimated to be 1.67–1.75. These low values suggest that this layer represents sedimentary rocks, and that the sand/shale ratio might be relatively high here. The V_p/V_s ratio in the crystalline basement is estimated to be 1.67–1.75 in the basin and on the landward part of the Vøring Plateau, indicating the presence of granitic/granodioritic continental crust. In the lower crust, the V_p/V_s ratio in the basin decreases uniformly from southwest to northeast, from 1.85–1.9 to 1.68–1.73, suggesting a gradual change from mafic (gabbroic) to felsic (granodioritic) lower crust. Significant (3–5%) azimuthal S-wave anisotropy is observed for several sedimentary layers, as well as in the lower crust. All these observations can be explained by invoking the presence of liquid-filled microcracks aligned vertically along the direction of the present day maximum compressive stress (NW–SE).     

Crustal transect from the North Atlantic Knipovich Ridge to the Svalbard Margin west of Hornsund

The crustal structure along a 312 km transect, stretching from the axial mountains of the North Atlantic Knipovich Ridge to the continental shelf of Svalbard, has been obtained using seismic reflection data and wide angle OBS data. The resulting seismic V_p and V_s models are further constrained by a 2-D-gravity model. The principal objective of this study is to describe and resolve the physical and compositional properties of the crust in order to understand the processes and creation of oceanic crust in this extremely slow-spreading counterpart of the North Atlantic Ridge Systems. V_p is estimated to be 3.50–6.05 km/s for the upper oceanic crust (oceanic layer 2), with a marked increase away from the ridge. The measured V_p of 6.55–6.95 km/s for oceanic layer 3A and 7.10–7.25 km/s for layer 3B, both with a V_p/V_s ratio of 1.81, except for slightly higher values at the ridge axis, does not allow a clear distinction between gabbro and mantle-derived peridotite (10–40% serpentized). The thickness of the oceanic crust varies a lot along the transect from the minimum of 5.6 km to a maximum of 8.1 km. The mean thickness of 6.7 km for the oceanic crust is well above the average thickness for slow-spreading ridges (<10 mm/year half-spreading rate). The areas of increased thickness could be explained by large magma production-rates found in the zones of axial highs at the ridge axis, which also have generated the off-axial highs adjacent the ridge. We suggest that these axial and off-axial highs along the ridge control the lithological composition of the oceanic crust. This approach suggests normal gabbroic oceanic crust to be found in the areas bound by the active magma segments (the axial and off-axial highs) and mantle-derived peridotite outside these zone.     

Scaling variables and interpretation of eigenvalues in principal component analysis of geologic data

The dominant feature distinguishing one method of principal components analysis from another is the manner in which the original data are transformed prior to the other computations. The only other distinguishing feature of any importance is whether the eigenvectors of the inner product-moment of the transformed data matrix are taken directly as the Q-mode scores or scaled by the square roots of their associated eigenvalues and called the R-mode loadings. If the eigenvectors are extracted from the product-moment correlation matrix, the variables, in effect, were transformed by column standardization (zero means and unit variances), and the sum of the p-largest eigenvalues divided by the sum of all the eigenvalues indicates the degree to which a model containing pcomponents will account for the total variance in the original data. However, if the data were transformed in any manner other than column standardization, the eigenvalues cannot be used in this manner, but can only be used to determine the degree to which the model will account for the transformed data. Regardless of the type of principal components analysis that is performed—even whether it is Ror Q-mode—the goodness-of-fit of the model to the original data is given better by the eigenvalues of the correlation matrix than by those of the matrix that was actually factored.     

Multivariate normality in morphometric analysis

Data on some living (salamanders and grasshoppers) and fossil (Devonian brachiopods) animals are analyzed by means of recently developed methods for the large-scale treatment of multivariate normality. Multivariate nonnormality was found to exist in all situations, even if the univariate deviations in the skewness and kurtosis statistics proved to be without significance for the most part. The effect of logarithmically transforming the data appears to be a mixed blessing. Apart from the fact that the investigator is removed one step from the biological relationships in his data by carrying out a transformation of them, the betterment in the multivariate interconnections with respect to normality tends to be slight, despite the general improvement in the univariate values. The relationship between sample size and the multivariate normality measures b_1,p and b_2,p are studied empirically.     

Ensemble smoothing of land subsidence measurements for reservoir geomechanical characterization

Geomechanical models are often used to predict the impact on land surface of fluid withdrawal from deep reservoirs, as well as investigating measures for mitigation. The ability to accurately simulate surface displacements, however, is often impaired by limited information on the geomechanical parameters characterizing the geological formations of interest. In this study, we employ an ensemble smoother, a data assimilation algorithm, to provide improved estimates of reservoir parameters through assimilation of measurements of both horizontal and vertical surface displacement into geomechanical model results. The method leverages the demonstrated potential of remote sensing techniques developed in the last decade to provide accurate displacement data for large areas of the land surface. For evaluation purposes, the methodology is applied to the case of a disk‐shaped reservoir embedded in a homogeneous, isotropic, and linearly elastic half space, subject to a uniform change in fluid pressure. Multiple sources of uncertainty are investigated, including the radius, R, the thickness, h, and the depth, c, of the reservoir; the pore pressure change, Δp; porous medium's vertical uniaxial compressibility, c_M, and Poisson's ratio, ν, and the ratio, s, between the compressibilities of the medium during loading and unloading cycles. Results from all simulations show that the ensemble smoother has the capability to effectively reduce the uncertainty associated with those parameters to which the variability and the spatial distribution of land surface displacements are most sensitive, namely, R, c, c_M, and s. These analyses demonstrate that the estimation of these parameters values depends on the number of measurements assimilated and the error assigned to the measurement values. Copyright © 2014 John Wiley & Sons, Ltd.     

Metamorphic evolution of the Maud Belt: P–T–t path for high-grade gneisses in Gjelsvikfjella, Dronning Maud Land, East Antarctica

A metamorphic petrological study, in conjunction with recent precise geochronometric data, revealed a complex P–T–t path for high-grade gneisses in a hitherto poorly understood sector of the Mesoproterozoic Maud Belt in East Antarctica. The Maud Belt is an extensive high-grade, polydeformed, metamorphic belt, which records two significant tectono-thermal episodes, once towards the end of the Mesoproterozoic and again towards the late Neoproterozoic/Cambrian. In contrast to previous models, most of the metamorphic mineral assemblages are related to a Pan-African tectono-thermal overprint, with only very few relics of late Mesoproterozoic granulite-facies mineral assemblages (M₁) left in strain-protected domains. Petrological and mineral chemical evidence indicates a clockwise P–T–t path for the Pan-African orogeny. Peak metamorphic (M_2b) conditions recorded by most rocks in the area (T = 709–785 °C and P = 7.0–9.5 kbar) during the Pan-African orogeny were attained subsequent to decompression from probably eclogite-facies metamorphic conditions (M_2a).The new data acquired in this study, together with recent geochronological and geochemical data, permit the development of a geodynamic model for the Maud Belt that involves volcanic arc formation during the late Mesoproterozoic followed by extension at 1100 Ma and subsequent high-grade tectono-thermal reworking once during continent–continent collision at the end of the Mesoproterozoic (M₁; 1090–1030 Ma) and again during the Pan-African orogeny (M_2a, M_2b) between 565 and 530 Ma. Post-peak metamorphic K-metasomatism under amphibolite-facies conditions (M_2c) followed and is ascribed to post-orogenic bimodal magmatism between 500 and 480 Ma.     

Diurnal variations of pCO2 in relation to environmental factors in the cascade reservoirs along the Wujiang River, China

We have investigated the diurnal variations of the pCO2 and related environmental factors in the cascade reservoirs with different trophic levels along Wujiang River. In surface water the pCO2 was 357±11 μatm in Hong-jiadu Reservoir, 338±48 μatm in Dongfeng Reservoir, 682±303 μatm in Wujiangdu Reservoir, and 1677±429 μatm in Liuguang, respectively. The results indicated that these cascade reservoirs had much lower pCO2 values in surface water than river did, and hypereutrophic reservoir showed larger diurnal variations of pCO2 than meso-eutrophic reservoir. In water column, pCO2 tended to increase with the depth. Phytoplankton and the environmental factors such as temperature and pH had different influences on pCO2 diurnal variations due to different trophic levels, and the effect of phytoplankton on pCO2 variation increased with the increase of trophic level in these reservoirs.     

曲线拟合新技术在分析高温高压实验数据中的试用

Kern(1982)和 Kern 与 Richter(1981)介绍了他们通过高温高压实验测定的、多种岩石在不同温度和压力条件下模拟地震 P 波和 S 波的波速 V_p 和 V_s,这些资料对于探索地壳内的岩石矿物组成和各种物理性质是十分宝贵的。我们知道,V_p 和 V_s 既依赖于温度,也依赖于压力。     

Toxicities of p-nitrotoluenes and their effects on blood corpuscles and ovaries in Crusian carps (Carassius auratus)

p-nitrotoluene is an important organic intermediate widely used in pesticide, foamed plastics, dyestuff and medicine industries. In this paper, Crusian carps (Carassius auratus) were exposed to dilute p-nitrotoluene solutions with different concentrations of 0, 20, 40, 80, 120, 160, 240 and 320 μg/L; the subsequent physiological responses to the chemical were observed, and the variation characteristics of blood corpuscles, ovaries and oocytes were studied by bio-microscopy. Results showed that even very low concentrations of p-nitrotoluene would lead to toxicosis and even the death of Carassius auratus. The bio-microscopic structures revealed that, compared with the compartment of Carassius auratus growing in the p-nitrotoluene-free water (the control group), the lower concentrations of p-nitrotoluene (for example no more than 80 μg/L) would result in the faster disintegration of erythrocytes and the significant enlargement of oocytes, while the higher contents of p-nitrotoluene (no less than 240 μg/L in this case) would inhibit the division of cells and their further growth, even degenerate blood corpuscles and ovaries, suggesting stronger estrogenic activities. The study is financially supported by the Development Foundation of Science and Technology under Shandong Provincial Education Department (No. J05D51).     

Vp/Vs Anisotropy and Implications for Crustal Composition Identification and Earthquake Prediction

Abstract: The ratio of P- to S-wave velocities (Vp/Vs) is regarded as one of the most diagnostic properties of natural rocks. It has been used as a discriminant of composition for the continental crust and provides valuable constraints on its formation and evolution processes. Furthermore, the spatial and temporal changes in Vp/Vs before and after earthquakes are probably the most promising avenue to understanding the source mechanics and possibly predicting earthquakes. Here we calibrate the variations in Vp/Vs in dry, anisotropic crustal rocks and provide a set of basic information for the interpretation of future seismic data from the Wenchuan earthquake Fault zone Scientific Drilling (WFSD) project and other surveys. Vp/Vs is a constant (Ф0) for an isotropic rock. However, most of crustal rocks are anisotropic due to lattice-preferred orientations of anisotropic minerals (e.g., mica, amphibole, plagioclase and pyroxene) and cracks as well as thin compositional layering. The Vp/Vs ratio of an anisotropic rock measured along a selected pair of propagation-vibration directions is an apparent value (Фij) that is significantly different from the value for its isotropic counterpart (Ф0). The usefulness of apparent Vp/Vs ratios as a diagnostic of crustal composition depends largely on rock seismic anisotropy. A 5% of P- and S-wave velocity anisotropy is sufficient to make it impossible to determine the crustal composition using the conventional criteria (Vp/Vs≤1.756 for felsic rocks, 1.7561.944 fluid-filled porous/fractured or partially molten rocks) if the information about the wave propagation-polarization directions with respect to the tectonic framework is unknown. However, the variations in Vp/Vs measured from borehole seismic experiments can be readily interpreted according to the orientations of the ray path and the polarization of the shear waves with respect to the present-day principal stress directions (i.e., the orientation of cracks) and the frozen fabric (i.e., foliation and lineation).     

铁细菌培养过程中低分子有机酸钠盐对含硫酸根铁矿物形成的影响

普遍存在环境中的低分子有机酸盐对氧化亚铁硫杆菌的矿化产物(施氏矿和黄钾铁矾等铁矿物)会产生影响,从而导致环境中有毒重金属迁移转化发生变化.本文探讨了低分子有机酸钠盐对铁细菌HX3成长过程中代谢产物铁矿物的影响,并利用XRD、FTIR、FESEM和EDS对形成的铁矿物进行了表征与分析.研究结果表明,低浓度低分子有机酸钠盐...     

Examination of the Chayes-Kruskal procedure for testing correlations between proportions

The Chayes-Kruskal procedure for testing correlations between proportions uses a linear approximation to the actual closure transformation to provide a null value,p _ij , against which an observed closed correlation coefficient,r _ij , can be tested. It has been suggested that a significant difference betweenp _ij andr _ij would indicate a nonzero covariance relationship between theith andjth open variables. In this paper, the linear approximation to the closure transformation is described in terms of a matrix equation. Examination of the solution set of this equation shows that estimation of, or even the identification of, significant nonzero open correlations is essentially impossible even if the number of variables and the sample size are large. The method of solving the matrix equation is described in the appendix.     

On comparative probabilities for normal confidence intervals by pearson's Types III and VII, and the Edgeworth series models for biotite data

Biotite crystals were counted in standard thin sections which originated from the diamond drill core of the mafic norite formation at Strathcona mine, Sudbury Nickel Irruptive. Pearson's method of moments is suitable to fit Types III and VII to the biotite data and its log ₁₀ transformation values, as the number of samples (thin sections)is large (351).Based on the two models and the Edgeworth series (utilizing the log ₁₀ data)probability values p,that biotite occurrences lie in the interval mean ± Z standard deviations is derived. Results are compared with the usual normal probability values p_Z corresponding to Zand it is shown that the Edgeworth series generated the largest pvalues for intervals when p_Z values are large; for intermediate or lower p_Z s. Types VII and III models produced larger ps, relative to the Normal and the Edgeworth series.     

Premonitory crustal deformations, strains and seismotectonic features (b-values) preceding Koyna earthquakes

There have been instances of premonitory variations in tilts, displacements, strains, telluric current, seismomagnetic effects, seismic velocities ( V_p, V_s) and their ratio (V_p/V_s), b-values, radon emission, etc. preceding large and moderate earthquakes, especially in areas near epicentres and along faults and other weak zones. Intensity and duration (T) of these premonitory quantities are very much dependent on magnitude (M) of the seismic event. Hence, these quantities may be utilised for prediction of an incoming seismic event well in advance of the actual earthquake. In the recent past, tilts, strain in deep underground rock and crustal displacements have been observed in the Koyna earthquake region over a decade covering pre- and postearthquake periods; and these observations confirm their reliability for qualitative as well as quantitative premonitory indices. Tilt began to change significantly one to two years before the Koyna earthquake of December 10, 1967, of magnitude 7.0. Sudden changes in ground tilt measured in a watertube tiltmeter accompanied an earthquake of magnitude 5.2 on October 17, 1973 and in other smaller earthquakes in the Koyna region, though premonitory changes in tilt preceding smaller earthquakes were not so much in evidence. However, changes in strains in deep underground rock were observed in smaller earthquakes of magnitude 4.0 and above. Furthermore, as a very large number of earthquakes (M = 1–7.0) were recorded in the extensive seismic net in the Koyna earthquake region during 1963–1975, precise b-value variations as computed from the above data, could reveal indirectly the state of crustal (tectonic) strain variations in the earthquake focal region and consequently act as a powerful premonitory index, especially for the significant Koyna earthquakes of December 10, 1967 (M = 7.0) and October 17, 1973 (M = 5.2). The widespread geodetic and magnetic levelling observations covering the pre- and postearthquake periods indicate significant vertical and horizontal crustal displacements, possibly accompanied by large-scale migration of underground magma during the large seismic event of December 10, 1967 in the Koyna region (M = 7.0). Duration (T) of premonitory changes in tilt, strains, etc., is generally governed by the equation of the type logT = A + BM (A and B are statistically determined coefficients). Similar other instances of premonitory evidences are also observed in micro-earthquakes (M = − 1 to 2) due to activation of a fault caused by nearby reservoir water-level fluctuations.     

Coseismic responses and the mechanism behind MW 5.1 earthquake of March 14, 2005 in the Koyna–Warna region, India

An earthquake of M_w 5.1 occurred on March 14, 2005, in the seismically active Koyna–Warna region in western India, the site known for the largest reservoir triggered seismicity (RTS) in the world. For more than four decades, earthquakes with M  4.0 have occurred in this region at regular intervals. Impoundment of reservoirs and changes in lake levels can trigger earthquakes by two processes of stress modifications, namely direct loading effect of the reservoir and diffusion through various faults and fractures. In this paper we analysed the reservoir water level data at Koyna and Warna reservoirs prior to the occurrence of the March 14, 2005 earthquake, to explain the dominant mechanism behind its occurrence and its correlation with the observed coseismic changes. We conclude that the diffusion process, not the reservoir load effect, is the dominating mechanism triggering earthquakes in the region. The coseismic changes in deep well water levels sensitive to earth tides are found to be to the order of 1–12 cm.     

Distribution of n-alkanes in lacustrine sediments from subtropical lake in Brazil

The geochemical composition of lake bed sediments of a tropical reservoir in Brazil have been investigated. The C, N, P composition showed almost no variation between the different sampling points. All samples contained inorganic phosphorus (IP) ranging from 52 to 70%. The Redfield ratios show that the lake is without significant anthropogenic inputs. Most of the organic matter is composed by higher plants decomposition revealed in the total organic carbon (TOC):nitrogen (N) ratio ranging from 15.4 to 57.2. Also, TOC:organic phosphorus (OP) ranged from 265.3 to 933.6, suggesting that most of the organic matter has terrestrial origin from wood plants. The ratios suggest that most organic matter is influenced by the terrestrial characteristics of the watershed. Furthermore, the relative abundance of n-alkane homologues in the sediments was investigated. All samples have been analyzed for the n-alkanes C₈ to C₄₀. The sediments were dominated by n-alkanes C₂₅–C₃₈. It is concluded that n-alkane in sediments mainly come from terrestrial plants, however there is a contribution of submerged aquatic plants, especially in those sites in deeper areas of the lake. On the basis of P_aq index the n-alkanes in sediments comes from terrestrial plants, however there is a contribution from emerged/floating plants.The investigated lake seems to be considered as meso to eutrophic. Because of the relatively high primary productivity in the lakes, there is a substantial organic-matter flux to the sediments, which rapidly becomes anoxic. According to the pristine/phytane ratio the sediments represent an anoxic environment with values found between 0.38 and 1.72.     

A late-glacial transition from Picea glauca to Picea mariana in southern New England

Picea is an important taxon in late-glacial pollen records from eastern North America, but little is known about which species of Picea were present. We apply a recently developed palynological method for discriminating the three Picea species in eastern North America to three records from New England. Picea glauca was dominant at  14,500–14,000 cal yr BP, followed by a transition to Picea mariana between  14,000 and 13,500 cal yr BP. Comparison of the pollen data with hydrogen isotope data shows clearly that this transition began before the beginning of the Younger Dryas Chronozone. The ecological changes of the late-glacial interval were not a simple oscillation in the position of a single species' range, but rather major changes in vegetation structure and composition occurring during an interval of variations in several environmental factors, including climate, edaphic conditions, and atmospheric CO₂ levels.     

Calcite dissolution kinetics in saline waters

The effect of ionic strength (I), pCO₂, and temperature on the dissolution rate of calcite was investigated in magnesium-free, phosphate-free, low calcium (m_Ca2+ ≈ 0.01 m) simple KCl and NaCl solutions over the undersaturation range of 0.4 ≤ Ω_calcite ≤ 0.8. First-order kinetics were found sufficient to describe the rate data where the rate constant (k) is dependent on the solution composition. Rates decreased with increasing I and were faster in KCl than NaCl solutions at the same I indicating that Na⁺ interacts more strongly with the calcite surface than K⁺ or that water is less available in NaCl solutions. Rates increased with increasing pCO₂ and temperature, and their influences diminished at high I. Arrhenius plots yielded a relatively high activation energy (E_a ≈ 20 ± 2 kJ mol^− 1) which indicated that dissolution was dominated by surface-controlled processes. The multiple regression model (MR) of Gledhill and Morse (2006a) was found to adequately describe the results at high I in NaCl solutions, but caution must be used when extrapolating to low I or pCO₂ values. These results are consistent with the hypothesis that the mole fraction of “free” solvent (X_{“free”H2O}) plays a significant role in the dissolution kinetics of calcite with a minimum value of  45–55% required for dissolution to proceed in undersaturated solutions at 25–55 °C and pCO₂ = 0.1–1 atm. This hypothesis has been incorporated into a modified version of the MR model of Gledhill and Morse (2006a) where X_{“free”H2O} has replaced I and the Ca²⁺ and Mg²⁺ terms have been dropped: